1. Field of the Invention
This invention relates to a striking head-interchangeable hammer, more particularly to a striking head-interchangeable hammer with a stress-distributable fastener.
2. Description of the Related Art
U.S. Pat. No. 6,655,236 discloses a conventional hammer device with interchangeable head members. The hammer device includes a handle, a head body with a threaded rod, and a plurality of striking head members, each of which has an inner thread that is threadedly engageable with the threaded rod of the head body. A counterforce acting on the striking head member on the head body is generated during a hammering operation of the hammer device. The counterforce pulls the striking head member away from the head body, and results in a stress concentrated on the threaded rod of the head body and the inner thread of the striking head member, which can cause loosening of the striking head member and damage to the threaded rod and the striking head member.